Metallic hydroxides and metallic-oxide hydroxides find the broadest application in the most diverse industrial fields, for example, as intermediate products of the production of metals themselves or of the corresponding metallic oxides, which are then in turn processed further, for example, into ceramics, etc.
Zinc hydroxides, for example, can be applied as preliminary stages for pigments, photoconductors (for example, in electrophotography), catalyst components (for example, in methanol synthesis), fluorescent substances, absorptive agents (for example, for the removal of H.sub.2 S from gases), etc. Zinc-oxide hydrates are suitable, for example, as a catalyst component for the oxidation of aromatics, iron(III) hydroxide is employed, for example, in water purification, for pharmaceutical purposes or for the manufacture of iron colorants, and cobalt(II) hydroxide can, for example, serve as a starting material for the production of siccatives. Many applications of the metallic hydroxides and metallic-oxide hydroxides concern especially their particulate form, the particle size of the same and their particle-size distribution.
Thus, in the chemical industry for example, Ni(II) hydroxide is utilized as a base chemical in the ceramic-products sector and especially in the construction of batteries. In addition to use as the positive electrode in commercial secondary cells, such as nickel-cadmium and nickel-iron battery systems, nickel hydroxide is being applied to an increasing degree in environmentally friendly nickel-metallic hydroxide batteries which contain no heavy metals. The active components of the batteries are the anode, consisting of a hydratable metal alloy which is free of heavy metals, and the cathode which consists of nickel hydroxide. The mass electrodes are installed in a gastight steel housing and separated by a plastic fleece. Determined by the mechanical structure of the battery, various requirements are imposed upon the product nickel hydroxide relative to morphology and appearance. The most uniform product possible with a spherical morphology and narrow particle-size distribution should be obtained to achieve good flowing behavior during the filling of the porous nickel-foam electrodes.